In the related art, for example, as described in Patent Documents 1 and 2, as an electrical wire for wires in a vehicle or a device, an electrical wire obtained by coating an electrical wire conductor, which is formed by twisting a plurality of copper wires together, with an insulating coat is provided. In addition, for efficient wiring or the like, a wire harness obtained by bundling a plurality of the above-described electrical wires is provided.
In recent years, from the viewpoint of environmental protection, there has been a strong demand for a decrease in the weight of a vehicle frame in order to reduce the amount of carbon dioxide discharged from a vehicle. Meanwhile, since there is progress not only in computerization of vehicles but also in the development of hybrid vehicles and electric vehicles, the number of electrical components used in a vehicle is increasing at an accelerating rate. Therefore, the amount of wire harnesses used to connect these components is estimated to be further increasing in the future, and there is a demand for a decrease in the weight of the wire harness.
Here, as means for decreasing the weight of the wire harness, an attempt has been made to decrease the diameters of an electrical wire and a copper wire. In addition, the decrease in the diameters of an electrical wire conductor and a copper wire decreases not only the weight but also the size of the wire harness, and thus there is another advantage in that the wiring space can be effectively used.
In addition, since a trolley wire for a railway, which is used for a train or the like, is in sliding contact with a power collection device such as a pantograph and is fed with power, it is necessary to ensure a certain degree of strength, wear resistance, conductivity, thermal resistance, and the like for the trolley wire.
In recent years, the travelling speed of a train has been increasing; however, when, in a high-speed railway such as Shinkansen, the travelling speed of a train becomes faster than the propagation speed of a wave generated in an overhead wire such as a trolley wire, the contact between the power collection device such as the pantograph and the trolley wire becomes unstable and thus there is a concern that it may become impossible to stably feed power to a train.
Here, since it becomes possible to increase the propagation speed of a wave in the trolley wire by increasing the overhead wire tension of the trolley wire, there is a demand for a trolley wire having a higher strength than before.
As a copper alloy wire having a high strength and a high conductivity which satisfy the above-described demanded characteristics, for example, as disclosed in Patent Documents 1 to 3, copper alloy wires containing Co, P, and Sn have been proposed. In these copper alloy wires, it becomes possible to improve the strength while ensuring the conductivity by precipitating a complex of Co and P in the matrix phase of copper.